It's going to be very hard. Federer has to avoid: Nole, Nadal and all the ballbashers.
Which is going to be really hard to do, it will be hard to avoid guys like Tsonga, Berdych and other big hitters in the slams. I honestly don't think Fed can get another major. 30 years, and competing in today's era just isn't very likely. Fed could do it in the 80's and early 90's maybe.